This application relates to spin torque transfer devices.
Spin torque transfer technology, also referred to as spin electronics, combines semiconductor technology and magnetics, and is a more recent development. In spin electronics, the spin of an electron, rather than the charge, is used to indicate the presence of digital information. The digital information or data, represented as a “0” or “1”, is storable in the alignment of magnetic moments within a magnetic element. The resistance of the magnetic element depends on the moment's alignment or orientation. The stored state is read from the element by detecting the component's resistive state.
The magnetic element, in general, includes a ferromagnetic pinned layer and a ferromagnetic free layer, each having a magnetization orientation, and a non-magnetic barrier layer therebetween. The magnetization orientations of the free layer and the pinned layer define the resistance of the overall magnetic element. Such an element is generally referred to as a “spin tunneling junction,” “magnetic tunnel junction” or the like. When the magnetization orientations of the free layer and pinned layer are parallel, the resistance of the element is low. When the magnetization orientations of the free layer and the pinned layer are antiparallel, the resistance of the element is high.
In order to sense the resistance of the magnetic element, current is driven through the magnetic element, either as current in plane (“CIP”) or current perpendicular to the plane (“CPP”). In the CIP configuration, current is driven parallel to the layers of the spin valve. In the CPP configuration, current is driven perpendicular to the layers of magnetic element.
At least because of their small size, it is desirous to use magnetic logic elements in many applications. It has been proposed that these spin electronic devices could be used as logic devices. A magnetic field generated by even small currents could program a magnetic element component to several “logic states”, i.e., higher resistance or lower resistance. Thus, it would be possible to sense or read the logic state by sending current through the programmed magnetic device and determining its resistance (i.e., whether it has high or low resistance). However, there are deficiencies in the proposed designs. Until this disclosure, complex logic functions can not be realized with magnetic logic devices employing magnetic fields. The present disclosure provides advanced programmable or reconfigurable magnetic devices that utilize an input magnetic element magnetostatically coupled to an output magnetic element.